Neutralizing monoclonal antibodies to respiratory syncytial virus

ABSTRACT

The present invention relates to the identification and cloning of a novel neutralizing human monoclonal antibody to the Respiratory Syncytial Virus. The invention provides such antibodies, fragments of such antibodies retaining RSV-binding ability, chimeric antibodies retaining RSV-binding ability, and pharmaceutical compositions including such antibodies. The invention further provides for isolated nucleic acids encoding the antibodies of the invention and host cells transformed therewith. Finally, the invention provides for diagnostic and therapeutic methods employing the antibodies and nucleic acids of the invention.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation (and claims the benefit of priorityunder 35 USC 120) of U.S. application Ser. No. 09/043,530, filed Oct. 9,1998, now abandoned, which is a 371 and claims priority of PCTApplication No. PCT/US96/14937, Sep. 18, 1996, which claims priorityfrom U.S. provisional application Ser. No. 60/003,931, Sep. 18, 1995.The disclosures of the prior applications are considered part of (andare incorporated by reference in) the disclosure of this application.

FIELD OF THE INVENTION

This invention relates generally to the field of immunology andspecifically to monoclonal antibodies which bind to and neutralizerespiratory syncytial virus (RSV).

BACKGROUND OF THE INVENTION

RSV represents a major health problem, worldwide. In the United Statesalone, there are currently approximately 250,000 new born infants andchildren per year who may develop severe or fatal RSV disease. RSV isthe major viral cause of severe pediatric lower respiratory tractdiseases, such as pneumonia and bronchiolitis, worldwvide. It alsoresults in a high rate of morbidity and mortality in infants or youngchildren with cardiopulmonary disease or an immunodeficiency.

In addition to the childhood population at risk (McIntosh and Chanock(1990) Virology, 2nd edn. (Fields and Knipe, eds) Raven Press, Ltd., NewYork, pp. 1045-1072), there is a considerable and increasingly largepopulation of immunosuppressed adults at risk due to the increasinglywidespread application of organ transplant, cancer/leukemia therapiessuch as bone marrow transplantation and the proliferation of HIVinfections in the homosexual population. HIV is now the leading killerof homosexuals in the 25-40 year age group, in the U.S.A. The aged, whorepresent a growing population in developing countries, also are at riskdue to immune deficiencies resulting from their acing immune systems,and RSV can be endemic in nursing home populations, particularly duringthe Winter season.

Whilst antibiotic therapy of bacterial infection has been successful inmany diseases, few antibiotics are available for therapy of viralinfections and none are currently available for effective treatment ofRSV infection. However the severity of viral infections is usually alsocorrelated with the immune status of the patient. For example, there isa correlation between levels of maternal IgG antibodies to RSV and theresistance of infants to infection during the first months of life, whenthe risk of severe disease is greatest (Ogilvie, et al., J. Med. Virol.7:263, 1981). Pooled human gamma globulin with high titer RSVneutralizing antibodies or RSV neutralizing murine monoclonal antibodiescan protect small animals from pulmonary infection with RSV and, whenadministered therapeutically, can be effective in small animals andprimates at the height of RSV infection (Walsh, et al., Infection andImmunity, 43:756, 1984; Prince, et al., J. Virol., 55:517, 1985; Prince,et al., Virus Research, 3:193,1985 Prince, et al., J. Virol., 61:1851,1987; Hemming, et al., J. Inf. Dis., 152:1083, 1985). Pooled human IgGcontaining RSV neutralizing antibodies has also been used clinically, totherapeutic effect, in a study of serious RSV disease in infants andyoung children (Hemming, et al., Antimicrob. Agnts. Chemotherap.,31:1882, 1987). However the use of pooled human sera for the treatmentof RSV infection has several drawbacks. Availability is limited. Batchesare not reproducible. Titers are 100 to 1,000 fold lower than formonoclonal antibody titers and the risk of iatrogenic infection isalways present when using human serum, due to the variable resistance ofmicroorganisms to the sterilization procedures utilized.

An RSV vaccine for active immunization, if available, could not beutilized for the treatment of newborn babies with immature immunesystems or patients who are immunosuppressed. In patients whereprophylactic passive immunotherapy is required, as a result of a morechronic form of disease, current therapy is mediated via periodicintravenous inoculation of human IgG prepared from pooled plasma. Thistype of therapy, due to the low titers of neutralizing anti-RSVantibodies, involves a large quantity of globulin (e.g., 0.75 gm per kg)and consequently requires administration intravenously, in a clinic orhospital, over a lengthy period (2 to 4 hours), on a monthly basisduring the high risk months (fall, winter and early spring).

The neutralizing component of human anti-RSV antibody preparations,derived from pooled human plasma, is only a minor fraction of the totalantibody present. The development of mouse monoclonal antibodytechnology thus provided cloned neutralizing antibodies of greaterspecific activity than the pooled human plasma preparations. Howeverproblems resulting from immune responses to the mouse antibodies, inhuman patients, have precluded the general application of thesepreparations for passive immunotherapy in humans. The development ofhuman monoclonal antibodies to RSV has been thwarted, until recently, bythe unsuccessful adaptation of monoclonal technology to the humansystem. Human hybridomas and immortalized EBV transformedB-lymphoblastoid cell lines, as well as mouse/human hybridomas aregenerally unstable antibody producers, even after multiple cloningsteps. The cloning and expression of human monoclonal antibodies, in E.coli utilizing phage (Huse et al., Science 246:1275-1281, 1989; Clacksonet al., Nature 352:624-628, 1991; Barbas et al., Proc. Natl. Acad. Sci.(USA): 88:7978-7982, 1991), has obviated this problem. RSV-specifichuman monoclonal antibody is now available with a 100 to 1000-foldhigher concentration of specific antibody than pooled plasmapreparations. The use of these human monoclonal antibody preparationswill correspondingly decrease the volume of antibody preparationsrequired for prophylaxis or therapy by the same order of magnitude.Effective doses of monoclonal antibody may now be administeredintramuscularly (i.m.), thereby reducing the period of time required.Prophylaxis in new born babies or infants can now be performed at home,as opposed to in the clinic or hospital, reducing inconvenience andeliminating the risk of hospital acquired RSV disease. This is inaddition to the inherent reduction in batch to batch variation ofmonoclonal antibody preparations and the reduction of the danger ofiatrogenic infections when compared to pooled human globulin. In fact,the reduced volumes of antibody preparations required for therapy willallow, in general, treatment of patients with RSV disease byadministration of antibodies intramuscularly. Aerosol therapy is anotherform of treatment made possible as a result of the increased specificactivity of monoclonal antibodies, and is also associated with adecrease in the amount of antibodies required. This type of therapy ishighly efficient due to the introduction of antibodies directly to thesite of infection in the lungs. The neutralizing ability of Fabfragments of the RSV monoclonal antibodies in vivo, by aerosolapplication or systemic therapy, has been well demonstrated.

Neutralizing epitopes on the RSV virus are mainly confined to the majorsurface antigens: the F glycoprotein (viral fusion) and G glycoprotein(viral attachment). Antiserum prepared against either glycoprotein F orglycoprotein G may neutralize RSV with high efficiency (Walsh, et al.,J. Gen. Microbiol., 67:505, 1986). However antibodies to glycoprotein Fare more frequently neutralizing for RSV. Antiserum to glycoprotein Falso inhibits fusion of RSV-infected cells to neighboring uninfectedcells. For therapeutic purposes, antibody preparations should neutralizea wide range of RSV isolates, including those of both antigenicsubgroups. There are two antigenic subgroups of RSV, A and B, which areeach present at all times in the population but which vary in proportionat any given time. Subgroups A and B are 50% related in glycoprotein Fat the DNA sequence level, but appear to be more highly related in theneutralization epitope regions. In contrast, subgroups A and B are only10% related in glycoprotein G (McIntosh and Chanock, supra). During thelast several years, the efficiency of topical immunotherapy for RSVinfection has been increased by two modifications of previousmethodology. First, a mixture of RSV F immune monoclonal antibodiesdirected at the major conserved neutralization epitopes on thisglycoprotein was shown effective in topical immunotherapy of RSVinfection in the cotton rat. Second, delivery of RSV polyclonalantibodies directly into the lungs in a small particle aerosol (lessthan 2 μm) was also effective therapeutically. The use of monoclonalantibodies should decrease the amount of IgG required for therapy by atleast 2 orders of magnitude. In other studies in cotton rats,parainfluenza virus type 3 (PIV3) antibodies were also shown to betherapeutic against PIV3 when administered directly into the respiratorytract. This form of topical immunotherapy has general application forrespiratory viral pathogens causing disease in the cells lining thelumen of the lower respiratory tract.

Humanized mouse monoclonal antibodies (MAb), due to the contribution ofthe grafted mouse CDR sequences, retain a significant proportion ofmouse sequence, representing 25-30% of the V-regions. There is noevidence to suggest any relationship between the mouse RSV 19 (Taylor etal., Immunology 52:137-142, 1984) and published human antibody V-regionCDR sequences (Winter et al., Eur. J. Immunol. 21:985-991, 1991) andhence repeated administration of humanized mouse MAb, as a consequenceof the surface location of the CDR regions on the antibody molecule, islikely to result in a human anti-mouse MAb (HAMMA) response. Thisresponse would then preclude further therapeutic use of the humanizedmouse MAb and in particular preclude any use of these humanized mouseMAb sequences for antibody gene therapy, in which case the therapy couldnot be withdrawn and might adversely affect the health of the patient.HAMMA responses are common in patients given conventional systemictherapy with mouse MAb, resulting in up to 50% of patients respondingafter the first dose and up to 95% of patients responding after thesecond dose. The use of pooled human gamma globulin has been universalfor prophylaxis in hepatitis and for treatment in hepatitis, Junin virusinduced hemorrhagic fever and RSV infection, with no side effects severeenough to preclude this form of passive immunization. Hence, byinference, the application of a human monoclonal Fab to this form oftherapy should have no serious consequence such as that induced by theHAMMA response to mouse antibody or fragments thereof.

For long term prophylaxis of RSV infection in immunosuppressed patientsor newborn infants who lack an intact immune system, it would bepreferable to apply an immunoglobulin preparation for passiveimmunization which includes more than one neutralizing epitope on theRSV F glycoprotein. This is due to the mutation rate of the RSV Fglycoprotein for any single neutralization site being in the range 10⁻⁴to 10⁻⁵, the rate for two neutralization sites being thus 10⁻⁸ to 10⁻¹⁰,for three neutralization sites being 10⁻¹² to 10⁻¹⁵ and so on.Administration of anti-RSV antibodies or fragments thereof, over asignificant period of time in multiple patients or as multiple periodsof treatment in a single patient, would create a significant selectivepressure for the development of escape mutants. Hence, to counteractthis selective pressure, the inclusion of antibodies or fragments to twoor more neutralization epitopes is preferable in any preparation to beused for passive immunization. However, prior to the present invention,only one other neutralizing human monoclonal RSV antibody or fragmentthereof, was known. The human Fab RSV 19 of Barbas et al. (Proc. Natl.Acad. Sci. (USA) 89:10164-10168, 1992), included in PCT InternationalPublication Number WO 94/06448, has an amino acid sequence completelyunrelated to those of the anti-RSV antibodies of the present invention.More important, the RSV19 human Fab binds to an unrelated neutralizationepitope on the RSV F glycoprotein epitope, representing the “B” epitopeor antigenic site, recognized by the mouse MAb 1269 (Taylor et al.,Immunology 52:137-142, 1984). Hence the uniqueness of the anti-RSVantibodies of the present invention and the human Fab RSV19, in both aasequence and epitopic site, has important implications for the design ofimmunotherapeutic vaccines or modalities for the treatment of RSVdisease.

SUMMARY OF THE INVENTION

The present invention relates to monoclonal antibodies which bind to anepitope on the RSV F glycoprotein which include amino acid (aa) residuenumber 429 or which bind to an epitope affected conformationally by asingle aa change at this position, and which neutralize with highefficiency antigenic subgroups A and B of respiratory syncytial virus(RSV). Also described are human immunoglobulin heavy chain and lightchain V-region amino acid sequences which confer neutralization functionto the paratope of these monoclonal antibodies. The monoclonalantibodies of the invention have particular utility as pharmaceuticalsand reagents for the immunoprophylaxis, immunotherapy and diagnosis ofRSV disease. The present invention also provides cell lines and vectorsproducing or encoding the monoclonal antibodies of the invention.

A major advantage of the monoclonal antibodies of the invention derivesfrom the fact that they include human CDR3 sequences and, in someembodiments, may be entirely human monoclonal antibodies. Hence in vivouse of the fully human monoclonal antibodies of the invention forimmunoprophylaxis and immunotherapy of RSV disease greatly reduces theproblem of host immune response to passively administered antibodies.This problem is commonly encountered when the prior art monoclonalantibodies of xenogeneic or chimeric derivation are utilized. A secondimportant aspect of this advantage is the potential safety of thesehuman monoclonal antibodies for gene therapy applications, in whichexpression of xenogeneic or chimeric proteins containing non-humansequences cannot be terminated.

The antibodies of the invention are particularly efficacious forimmunotherapy of RSV disease when administered directly to the lungs inthe form of Fab fragments. Topical delivery of RSV antibodies directlyinto the lungs has a major advantage over parenteral administration ofantibodies for therapy of RSV disease. Polyclonal antibodies deliveredby the former route are approximately 80 to 160 times more effective intherapy, thereby decreasing the amount of antibody required for therapyby a factor of 80 to 160. A further reduction in the amount of antibodyrequired for therapy by a factor of 25 to 50, can be achieved by usingmonoclonal rather than polyclonal antibodies. This means that the totalamount of antibody required for therapy by parenteral treatment can bereduced by a factor of 2000 to 8000 when monoclonal antibodies areadministered directly into the lungs for treatment of RSV infection. Theability to utilize Fab or Fd fragments in vivo for respiratory viralinfections provides significant advantages over the use of wholeantibody molecules including: (1) greater tissue penetration; (2)avoidance of effector functions associated with Fc such as inflammation;and (3) rapid clearance.

The in vivo therapeutic effectiveness of Fab fragments in treating viralinfection has been demonstrated for RSV and coronaviruses. This isdespite the fact that Fabs are monovalent, precluding antigen crosslinking, which was commonly thought to be necessary for viralneutralization; and that the Fc portion was thought to be necessary forviral clearance as a consequence of complement activation and antibodydependent cell cytotoxicity (ADCC).

In particular, the present invention provides substantially purepolypeptides comprising antibodies selectively binding to an RSV Fglycoprotein epitope, wherein the antibodies include a heavy chain CDR3region having the RSVF2-5 heavy chain CDR3 amino acid sequence of SEQ IDNO: 7. Such antibodies include fragment antibodies which are Fd, Fv andFab fragments. The invention further provides such antibodies whichinclude the heavy chain CDR2 region of SEQ ID NO: 5, and/or the heavychain CDR1 region of SEQ ID NO: 3. In particularly preferredembodiments, the antibodies of the invention include the entire RSVF2-5heavy chain Fd sequence of SEQ ID NO: 1.

In some embodiments, the antibodies of the invention are Fab fragmentsand further include the light chain CDR3 region of SEQ ID NO: 15, thelight chain CDR2 region of SEQ ID NO: 13, and/or the light chain CDR1region having the amino acid sequence of SEQ ID NO: 11. In particularlypreferred embodiments the antibodies of the present invention includethe entire RSVF2-5 light chain sequence of SEQ ID NO: 9.

Because the major antigen binding domain of antibodies is the heavychain CDR3 region, the present invention also provides polypeptideswhich consist of, or consist essentially of, the heavy chain CDR3 regionof the RSVF2-5 antibody disclosed as SEQ ID NO: 7.

The present invention also provides pharmaceutical preparationscomprising a pharmaceutically acceptable carrier and any one or more ofthe antibodies described above.

In another series of embodiments, the present invention also providesisolated nucleic acids comprising nucleotide sequences encoding theantibodies described above. In particular, the present inventionprovides such nucleic acids in the form of vectors including regulatorysequences operably joined to said nucleotide sequences.

The present invention also provides pharmaceutical preparationscomprising a pharmaceutically acceptable carrier; and any one or more ofthe nucleic acids described above.

In another set of embodiments, the present invention provides a methodfor the treatment of RSV disease comprising administering to a human orother animal subject in need of such treatment a therapeuticallyeffective amount of the antibody and/or nucleic acid pharmaceuticalcompositions described above. The methods can be for prophylaxis of RSVinfection or for treatment of active RSV disease.

In yet another set of embodiments, the present invention provides amethod of detecting the presence of RSV in a biological samplecomprising contacting such a sample with any one or more of theantibodies described above. In another set of embodiments, the inventionprovides a method of detecting the presence of RSV in vivo comprisingcontacting a subject With an effective amount of any one or more of theantibodies described above, the antibodies contained in apharmaceutically acceptable carrier. Binding of the antibodies to RSV,then can be detected as a determination of the presence of RSV.

The invention also involves the use of the antibodies and/or nucleicacids described above in the preparation of a medicament. The medicamentcan be for any of the diagnostic and/or therapeutic purposes discussedherein.

Finally, the present invention provides host cells including a vectorcomprising a nucleic acid encoding one of the antibodies of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

Definitions.

As used herein, the term “antibody” means an immunoglobulin molecule ora fragment of an immunoglobulin molecule having the ability tospecifically bind to a particular antigen. Antibodies are well known tothose of ordinary skill in the science of immunology. As used herein,the term “antibody” means not only intact antibody molecules but alsofragments of antibody molecules retaining antigen binding ability. Suchfragments are also well known in the art and are regularly employed bothin vitro and in vivo. In particular, as used herein, the term “antibody”means not only intact immunoglobulin molecules but also antigen bindingactive fragments such as the well-known active fragments F(ab′)₂, Fab,Fv, and Fd.

As used herein, the term RSV “disease” means any disease caused,directly or indirectly, by a Respiratory Syncytial Virus (RSV) as wellas diseases or conditions which predispose a patient to infection byRSV. Examples of diseases falling into the former category includepneumonia and bronchiolitis. Diseases and conditions in the lattercategory (i.e., those which place the patient at risk of severe RSVinfection) include cystic fibrosis, congenital heart disease, cancer,age related immunosuppression and, generally, any condition that causesa state of immunosuppression or decreased function of the immune systemsuch as post-operative organ transplantation regimens or prematurebirth.

As used herein with respect to polypeptides, the term “substantiallypure” means that the polypeptides are essentially free of othersubstances with which they may be found in nature or in vivo systems toan extent practical and appropriate for their intended use. Inparticular, the polypeptides are sufficiently pure and are sufficientlyfree from other biological constituents of their hosts cells so as to beuseful in, for example, generating antibodies sequencing, or producingpharmaceutical preparations. By techniques well known in the art,substantially pure polypeptides may be produced in light of the nucleicacid and amino acid sequences disclosed herein. Because a substantiallypurified polypeptide of the invention may be admixed with apharmaceutically acceptable carrier in a pharmaceutical preparation, thepolypeptide may comprise only a small percentage by weight of thepreparation. The polypeptide is nonetheless substantially pure in thatit has been substantially separated from the substances with which itmay be associated in living systems.

As used herein with respect to nucleic acids, the tern “isolated” means:(I) amplified in vitro by, for example, polymerase chain reaction (PCR);(ii) recombinantly produced by cloning; (iii) purified, as by cleavageand gel separation; or (iv) synthesized by, for example, chemicalsynthesis. An isolated nucleic acid is one which is readily manipulableby recombinant DNA techniques well known in the art. Thus, a nucleotidesequence contained in a vector in which 5′ and 3′ restriction sites areknown or for which polymerase chain reaction (PCR) primer sequences havebeen disclosed is considered isolated but a nucleic acid sequenceexisting in its native state in its natural host is not. An isolatednucleic acid may be substantially purified, but need not be. Forexample, a nucleic acid that is isolated within a cloning or expressionvector is not pure in that it may comprise only a tiny percentage of thematerial in the cell in which it resides. Such a nucleic acid isisolated, however, as the term is used herein because it is readilymanipulable by standard techniques known to those of ordinary skill inthe art.

As used herein, a coding sequence and regulatory sequences are said tobe “operably joined” when they are covalently linked in such a way as toplace the expression or transcription of the coding sequence under theinfluence or control of the regulatory sequences. If it is desired thatthe coding sequences be translated into a functional protein, two DNAsequences are said to be operably joined if induction of a promoter inthe 5′ regulatory sequences results in the transcription of the codingsequence and if the nature of the linkage between the two DNA sequencesdoes not (1) result in the introduction of a frame-shift mutation, (2)interfere with the ability of the promoter region to direct thetranscription of the coding sequences, or (3) interfere with the abilityof the corresponding RNA transcript to be translated into a protein.Thus, a promoter region would be operably joined to a coding sequence ifthe promoter region were capable of effecting transcription of that DNAsequence such that the resulting transcript might be translated into thedesired protein or polypeptide.

The precise nature of the regulatory sequences needed for geneexpression may vary between species or cell types, but shall in generalinclude, as necessary, 5′ non-transcribing and 5′ non-translatingsequences involved with initiation of transcription and translationrespectively, such as a TATA box, capping sequence, CAAT sequence, andthe like. Especially, such 5′ non-transcribing regulatory sequences willinclude a promoter region which includes a promoter sequence fortranscriptional control of the operably joined gene. Regulatorysequences may also include enhancer sequences or upstream activatorsequences, as desired.

As used herein, a “vector” may be any of a number of nucleic acids intowhich a desired sequence may be inserted by restriction and ligation fortransport between different genetic environments or for expression in ahost cell. Vectors are typically composed of DNA although RNA vectorsare also available. Vectors include, but are not limited to, plasmidsand phagemids. A cloning vector is one which is able to replicate in ahost cell, and which is further characterized by one or moreendonuclease restriction sites at which the vector may be cut in adeterminable fashion and into which a desired DNA sequence may beligated such that the new recombinant vector retains its ability toreplicate in the host cell. In the case of plasmids, replication of thedesired sequence may occur many times as the plasmid increases in copynumber within the host bacterium or just a single time per host beforethe host reproduces by mitosis. In the case of phage replication mayoccur actively during a lytic phase or passively during a lysogenicphase. An expression vector is one into which a desired DNA sequence maybe inserted by restriction and ligation such that it is operably joinedto regulatory sequences and may be expressed as an RNA transcript.Vectors may further contain one or more marker sequences suitable foruse in the identification of cells which have or have not beentransformed or transfected with the vector. Markers include, forexample, genes encoding proteins which increase or decrease eitherresistance or sensitivity to antibiotics or other compounds, genes whichencode enzymes whose activities are detectable by standard assays knownin the art (e.g., β-galactosidase or alkaline phosphatase), and geneswhich visibly affect the phenotype of transformed or transfected cells,hosts, colonies or plaques. Preferred vectors are those capable ofautonomous replication and expression of the structural gene productspresent in the DNA segments to which they are operably joined.

Novel Anti-RSV Monoclonal Antibodies

The present invention derives, in part, from the isolation andcharacterization of a novel, fully human monoclonal antibody whichselectively binds to and neutralizes RSV and which we have designatedRSVF2-5. As described more fully below, this new monoclonal antibody hasbeen shown to bind to the RSV F glycoprotein and to neutralize RSV invivo. The paratope of the RSVF2-5 Fab fragment associated with theneutralization epitope on the RSV F glycoprotein F1 subunit is definedby the amino acid (aa) sequences of the immunoglobulin heavy and lightchain V-regions depicted in Table 5 and SEQ ID NO: 1 and SEQ ID NO: 9.The nucleic acid sequences coding for these aa sequences were identifiedas described in Example 1, by sequencing from both the 5′ and 3′ ends ofthe Fd heavy chain fragment and light chain. These nucleic acidsequences have been deposited with the National Center for GenomeResources (accession numbers L41061 and L41062) and are disclosed hereinas SEQ ID NO: 21 and SEQ ID NO: 22 However, due to the degeneracy of theDNA code, the paratope is more properly defined by the derived aasequences depicted in Table 5, in SEQ ID NO: 1 and SEQ ID NO: 9.

The antibodies of the present invention selectively bind to an epitopeon the RSV F glycoprotein which either includes amino acid (aa) residuenumber 429 or which is affected conformationally by a single aa changeat this position. This is demonstrated by the ability of the antibodiesof the present invention to neutralize RSV strains in which position 429of the RSV F glycoprotein is occupied by an arginine residue but not anRSV strain in which this position is occupied by a serine residue (seeExample 3, Table 4). A murine antibody and humanized murine antibodiesspecific for a similar, if not identical. RSV epitope were described inPCT International Publication Number WO 92/04381. Of particularimportance, the antibodies of the present invention are specific for,and neutralize, both the A and B antigenic subgroups of the respiratorysyncytial virus.

In one set of embodiments, the present invention provides the intactfully human RSVF2-5 monoclonal antibody in isolated form and inpharmaceutical preparations. Similarly, as described below, the presentinvention provides isolated nucleic acids, host cells transformed withnucleic acids, and pharmaceutical preparations including isolatednucleic acids, encoding the intact, fully human RSVF2-5 monoclonalantibody. Finally, the present invention provides methods, as describedmore fully below, employing these antibodies and nucleic acids in the invitro and in vivo diagnosis and therapy of RSV disease.

Significantly, as is well-known in the art, only a small portion of anantibody molecule, the paratope, is involved in the binding of theantibody to its epitope (see, in general, Clark, W. R. (1986) TheExperimental Foundations of Modem Immunology Wiley & Sons, Inc., NewYork; Roitt, I. (1991) Essential Immunology, 7th Ed., BlackwellScientific Publications, Oxford). The pFc′ and Fc regions, for example,are effectors of the complement cascade but are not involved in antigenbinding. An antibody from which the pFc′ region has been enzymaticallycleaved, or which has been produced without the pFc′ region, designatedan F(ab′)₂ fragment, retains both of the antigen binding sites of anintact antibody. Similarly, an antibody from which the Fc region hasbeen enzymatically cleaved, or which has been produced without the Fcregion, designated an Fab fragment, retains one of the antigen bindingsites of an intact antibody molecule. Proceeding further, Fab fragmentsconsist of a covalently bound antibody light chain and a portion of theantibody heavy chain denoted Fd. The Fd fragments are the majordeterminant of antibody specificity (a single Fd fragment may beassociated with up to ten different light chains without alteringantibody specificity) and Fd fragments retain epitope-binding ability inisolation. Within the antigen-binding portion of an antibody, as iswell-known in the art, there are complementarity determining regions(CDRs), which directly interact with the epitope of the antigen, andframework regions (FRs), which maintain the tertiary structure of theparatope (see, in general, Clark, 1986; Roitt, 1991). In both the heavychain Fd fragment and the light chain of IgG immunoglobulins, there arefour framework regions (FR1 through FR4) separated respectively by threecomplementarity determining regions (CDR1 through CDR3). The CDRs, andin particular the CDR3 regions, and more particularly the heavy chainCDR3, are largely responsible for antibody specificity.

The complete amino acid sequences of the antigen-binding Fab portion ofthe RSVF2-5 monoclonal antibody as well as the relevant FR and CDRregions are disclosed herein. SEQ ID NO: 1 discloses the amino acidsequence of the Fd fragment of RSVF2-5. The amino acid sequences of theheavy chain FR1, CDR1, FR2, CDR2, FR3, CDR3 and FR4 regions aredisclosed as SEQ ID NO: 2 through SEQ ID NO: 8, respectively. SEQ ID NO:9 discloses the amino acid sequence of the light chain of RSVF2-5. Theamino acid sequences of the light chain FR1, CDR1, FR2, CDR2, FR3, CDR3and FR4 regions are disclosed as SEQ ID NO: 10 through SEQ ID NO: 16,respectively.

It is now well-established in the art that the non-CDR regions of amammalian antibody may be replaced with similar regions of conspecificor heterospecific antibodies while retaining the epitopic specificity ofthe original antibody. This is most clearly manifested in thedevelopment and use of “humanized” antibodies in which non-human CDRsare covalently joined to human FR and/or Fc/pFc′ regions to produce afunctional antibody. Thus, for example, PCT International PublicationNumber WO 92/04381 teaches the production and use of humanized murineRSV antibodies in which at least a portion of the murine FR regions havebeen replaced by FR regions of human origin. Such antibodies, includingfragments of intact antibodies with antigen-binding ability, are oftenreferred to as “chimeric” antibodies.

Thus, as will be apparent to one of ordinary skill in the art, thepresent invention also provides for F(ab′)₂, Fab, Fv and Fd fragments ofthe RSVF2-5 monoclonal antibody; chimeric antibodies in which the Fcand/or FR and/or CDR1 and/or CDR2 and/or light chain CDR3 regions of theRSVF2-5 antibody have been replaced by homologous human or non-humansequences; chimeric F(ab′)₂ fragment antibodies in which the FR and/orCDR1 and/or CDR2 and/or light chain CDR3 regions of the RSVF2-5 antibodyhave been replaced by homologous human or non-human sequences; chimericFab fragment antibodies in which the FR and/or CDR1 and/or CDR2 and/orlight chain CDR3 regions have been replaced by homologous human ornon-human sequences; and chimeric Fd fragment antibodies in which the FRand/or CDR1 and/or CDR2 regions have been replaced by homologous humanor non-human sequences. Thus, those skilled in the art may alter theRSVF2-5 antibody by the construction of CDR grafted or chimericantibodies or antibody fragments containing, all or part thereof, of thedisclosed heavy and light chain V-region CDR aa sequences (Jones et al.,Nature 321:522, 1986; Verhoeyen et al., Science 39:1534, 1988 andTempest et al., Bio/Technology 9:266, 1991), without destroying thespecificity of the antibodies for the RSV F glycoprotein epitope. SuchCDR grafted or chimeric antibodies or antibody fragments can beeffective in prevention and treatment of RSV infection in animals (e.g.cattle) and man.

In preferred embodiments, the chimeric antibodies of the invention arefully human monoclonal antibodies including at least the heavy chainCDR3 region of the RSVF2-5 antibody. As noted above, such chimericantibodies may be produced in which some or all of the FR regions ofRSVF2-5 have been replaced by other homologous human FR regions. Inaddition, the Fc portions may be replaced so as to produce IgA or IgM aswell as IgG antibodies bearing some or all of the CDRs of the RSVF2-5antibody. Of particular importance is the inclusion of the RSVF2-5 heavychain CDR3 region and, to a lesser extent, the other CDRs of RSVF2-5.Such fully human chimeric antibodies will have particular utility inthat they will not evoke an immune response against the antibody itself.

It is also possible, in accordance with the present invention, toproduce chimeric antibodies including non-human sequences. Thus, one mayuse, for example, murine, ovine, equine, bovine or other mammalian Fc orFR sequences to replace some or all of the Fc or FR regions of theRSVF2-5 antibody. Some of the CDRs may be replaced as well. Again,however, it is preferred that at least the heavy chain CDR3 region ofthe RSVF2-5 antibody be included in such chimeric antibodies and, to alesser extent, it is also preferred that some or all of the other CDRsof RSVF2-5 be included. Such chimeric antibodies bearing non-humanimmunoglobulin sequences admixed with the CDRs of the human RSVF2-5monoclonal antibody are not preferred for use in humans and areparticularly not preferred for extended use because they may evoke animmune response against the non-human sequences. They may, of course, beused for brief periods or in immunosuppressed individuals but, again,fully human antibodies are preferred. Because, however, RSV also infectsanimals such as cattle, and because such antibodies may be used forbrief periods or in immunosuppressed subjects, chimeric antibodiesbearing non-human mammalian Fc and FR sequences but including at leastthe RSVF2-5 heavy chain CDR3 are contemplated as alternative embodimentsof the present invention.

For inoculation or prophylactic uses, the antibodies of the presentinvention are preferably intact antibody molecules including the Fcregion. Such intact antibodies will have longer half-lives than smallerfragment antibodies (e.g. Fab) and are more suitable for intravenous,intraperitoneal, intramuscular, intracavity, subcutaneous, ortransdermal administration.

When administered topically to the lumenal lining of the lungs, as byaerosol, Fab fragments, including chimeric Fab fragments, are preferred.Fabs offer several advantages over F(ab′)₂ and whole immunoglobulinmolecules for this therapeutic modality. First, because Fabs have onlyone binding site for their cognate antigen, the formation of immunecomplexes is precluded whereas such complexes can be generated whenbivalent F(ab′)₂ s and whole immunoglobulin molecules encounter theirtarget antigen. This is of some importance because immune complexdeposition in tissues can produce adverse inflammatory reactions.Second, because Fabs lack an Fc region they cannot trigger adverseinflammatory reactions that are activated by Fc, such as activation ofthe complement cascade. Third, the tissue penetration of the small Fabmolecule is likely to be much better than that of the larger wholeantibody. Fourth, Fabs can be produced easily and inexpensively inbacteria, such as E. coli, whereas whole immunoglobulin antibodymolecules require mammalian cells for their production in usefulamounts. The latter entails transfection of immunoglobulin sequencesinto mammalian cells with resultant transformation. Amplification ofthese sequences must then be achieved by rigorous selective proceduresand stable transformants must be identified and maintained. The wholeimmunoglobulin molecules must be produced by stably transformed, highexpression mammalian cells in culture with the attendant problems ofserum-containing culture medium. In contrast, production of Fabs in E.coli eliminates these difficulties and makes it possible to producethese antibody fragments in large fermenters which are less expensivethan cell culture-derived products.

In addition to Fabs, smaller antibody fragments and epitope-bindingpeptides having binding specificity for the RSVF2-5 epitope of RSV arealso contemplated by the present invention and can also be used toneutralize the virus. For example, single chain antibodies can beconstructed according to the method of U.S. Pat. No. 4,946,778, toLadner et al., which is incorporated herein by reference. Single chainantibodies comprise the variable regions of the light and heavy chainsjoined by a flexible linker moiety. Yet smaller is the antibody fragmentknown as the single domain antibody or Fd, which comprises an isolatedVH single domain. Techniques for obtaining a single domain antibody withat least some of the binding specificity of the intact antibody fromwhich they are derived are known in the art. For example, Ward, et al.Nature 341: 644-646 (1989), disclose a method of screening to identifyan antibody heavy chain variable region (V_(H) single domain antibody)with sufficient affinity for its target epitope to bind thereto inisolated form.

It is possible to determine, without undue experimentation, if analtered or chimeric antibody has the same specificity as the RSVF2-5antibody of the invention by ascertaining whether the former blocks thelatter from binding to RSV. If the monoclonal antibody being testedcompetes with the RSVF2-5 antibody, as shown by a decrease in binding ofthe RSVF2-5 antibody, then it is likely that the two monoclonalantibodies bind to the same or a closely related, epitope. Still anotherway to determine whether a monoclonal antibody has the specificity ofthe RSVF2-5 antibody of the invention is to pre-incubate the RSVF2-5antibody With RSV with which it is normally reactive, and then add themonoclonal antibody being tested to determine if the monoclonal antibodybeing tested is inhibited in its ability to bind RSV. If the monoclonalantibody being tested is inhibited then, in all likelihood, it has thesame, or a functionally equivalent, epitope and specificity as theRSVF2-5 antibody of the invention. Screening of monoclonal antibodies ofthe invention, also can be carried out utilizing RSV and determiningwhether the monoclonal antibody neutralizes RSV.

By using the antibodies of the invention, it is now possible to produceanti-idiotypic antibodies which can be used to screen other monoclonalantibodies to identify whether the antibody has the same bindingspecificity as an antibody of the invention. In addition, suchanti-idiotypic antibodies can be used for active immunization (Herlyn,et al., Science, 232:100, 1986). Such anti-idiotypic antibodies can beproduced using well-known hybridoma techniques (Kohler and Milstein,Nature, 256:495, 1975). An anti-idiotypic antibody is an antibody whichrecognizes unique determinants present on the monoclonal antibodyproduced by the cell line of interest. These determinants are located inthe hypervariable region of the antibody. It is this region which bindsto a given epitope and, thus, is responsible for the specificity of theantibody. An anti-idiotypic antibody can be prepared by immunizing ananimal with the monoclonal antibody of interest. The immunized animalwill recognize and respond to the idiotypic determinants of theimmunizing antibody and produce an antibody to these idiotypicdeterminants. By using the anti-idiotypic antibodies of the immunizedanimal, which are specific for the monoclonal antibodies of theinvention, it is possible to identify other clones with the sameidiotype as the antibody of the hybridoma used for immunization.Idiotypic identity between monoclonal antibodies of two cell linesdemonstrates that the two monoclonal antibodies are the same withrespect to their recognition of the same epitopic determinant. Thus, byusing anti-idiotypic antibodies, it is possible to identify otherhybridomas expressing monoclonal antibodies having the same epitopicspecificity.

It is also possible to use the anti-idiotype technology to producemonoclonal antibodies which mimic an epitope. For example, ananti-idiotypic monoclonal antibody made to a first monoclonal antibodywill have a binding domain in the hypervariable region which is theimage of the epitope bound by the first monoclonal antibody. Thus, theanti-idiotypic monoclonal antibody can be used for immunization, sincethe anti-idiotype monoclonal antibody binding domain effectively acts asan antigen.

Nucleic Acids Encoding Anti-RSV Antibodies

Given the disclosure herein of the amino acid sequences of the heavychain Fd and light chain variable domains of the RSVF2-5 anti-RSVantibody, one of ordinary skill in the art is now enabled to producenucleic acids which encode this antibody or which encode the variousfragment antibodies or chimeric antibodies described above. It iscontemplated that such nucleic acids will be operably joined to othernucleic acids forming a recombinant vector for cloning or for expressionof the antibodies of the invention. The present invention includes anyrecombinant vector containing the coding sequences, or part thereof,whether for prokaryotic or eukaryotic transformation, transfection orgene therapy. Such vectors may be prepared using conventional molecularbiology techniques, known to those with skill in the art, and wouldcomprise DNA coding sequences for the RSVF2-5 immunoglobulin V-regionsincluding framework and CDRs or parts thereof, and a suitable promotereither with (Whittle et al., Protein Eng. 1:499, 1987 and Burton et al.,Science 266:1024-1027, 1994) or without (Marasco et al., Proc. Natl.Acad. Sci. (USA) 90:7889, 1993 and Duan et al., Proc. Natl. Acad. Sci.(USA) 91:5075-5079,1994) a signal sequence for export or secretion. Suchvectors may be transformed or transfected into prokaryotic (Huse et al.,Science 246:1275, 1989, Ward et al., Nature 341: 644-646, 1989; Marks etal., J. Mol. Biol. 222:581, 1991 and Barbas et al., Proc. Natl. Acad.Sci. (USA) 88:7978, 991) or eukaryotic (Whittle et al., 1987 and Burtonet al., 1994) cells or used for gene therapy (Marasco et al., 1993 andDuan et al., 1994) by conventional techniques, known to those with skillin the art.

The expression vectors of the present invention include regulatorysequences operably joined to a nucleotide sequence encoding one of theantibodies of the invention. As used herein, the term “regulatorysequences” means nucleotide sequences which are necessary for orconducive to the transcription of a nucleotide sequence which encodes adesired polypeptide and/or which are necessary for or conducive to thetranslation of the resulting transcript into the desired polypeptide.Regulatory sequences include, but are not limited to, 5′ sequences suchas operators, promoters and ribosome binding sequences, and 3′ sequencessuch as polyadenylation signals. The vectors of the invention mayoptionally include 5′ leader or signal sequences, 5′ or 3′ sequencesencoding fusion products to aid in protein purification, and variousmarkers which aid in the identification or selection of transformants.The choice and design of an appropriate vector is within the ability anddiscretion of one of ordinary skill in the art. The subsequentpurification of the antibodies may be accomplished by any of a varietyof standard means known in the art.

A preferred vector for screening monoclonal antibodies, but notnecessarily preferred for the mass production of the antibodies of theinvention is a recombinant DNA molecule containing a nucleotide sequencethat codes for and is capable of expressing a fusion polypeptidecontaining, in the direction of amino- to carboxy-terminus, (1) aprokaryotic secretion signal domain, (2) a polypeptide of the invention,and, optionally, (3) a fusion protein domain. The vector includes DNAregulatory sequences for expressing the fusion polypeptide, preferablyprokaryotic regulatory sequences. Such vectors can be constructed bythose with skill in the art and have been described by Smith et al.(Science 228:1315-1317, 1985), Clackson et al. (Nature 352:624-628,1991); Kang et al. (in “Methods: A Companion to Methods in Enzymology:Vol. 2”, R. A. Lerner and D. R. Burton, ed. Academic Press, NY, pp111-118,1991); Barbas et al. (Proc. Natl. Acad. Sci. (USA) 88:7978-7982,1991). Roberts et al. (Proc. Natl. Acad. Sci. (USA) 89:2429-2433, 1992)

A fusion polypeptide may be useful for purification of the antibodies ofthe invention. The fusion domain may, for example, include a poly-Histail which allows for purification on Ni+ columns or the maltose bindingprotein of the commercially available vector pMAL (New England BioLabs,Beverly. Mass.). A currently preferred, but by no means necessary,fusion domain is a filamentous phage membrane anchor. This domain isparticularly useful for screening phage display libraries of monoclonalantibodies but may be of less utility for the mass production ofantibodies; The filamentous phage membrane anchor is preferably a domainof the cpIII or cpVIII coat protein capable of associating with thematrix of a filamentous phage particle, thereby incorporating the fusionpolypeptide onto the phage surface, to enable solid phase binding tospecific antigens or epitopes and thereby allow enrichment and selectionof the specific antibodies or fragments encoded by the phagemid vector.

The secretion signal is a leader peptide domain of a protein thattargets the protein membrane of the host cell, such as the periplasmicmembrane of gram negative bacteria. A preferred secretion signal for E.coli is a pelB secretion signal. The predicted amino acid residuesequences of the secretion signal domain from two pelB gene producingvariants from Erwinia carotova are described in Lei, et al. (Nature381:543-546, 1988). The leader sequence of the pelB protein haspreviously been used as a secretion signal for fusion proteins (Better,et al., Science 240:1041-1043, 1988; Sastry et al., Proc. Natl. Acad.Sci (USA) 86:5728-5732, 1989; and Mullinax, et al., Proc. Natl. Acad.Sci. (USA) 87:8095-8099, 1990). Amino acid residue sequences for othersecretion signal polypeptide domains from E. coli useful in thisinvention can be found in Oliver. In Neidhard, F. C. (ed.), Escherichiacoli and Salmonella Typhimurium, American Society for Microbiology,Washington, D.C., 1:56-69 (1987).

To achieve high levels of gene expression in E. coli, it is necessary touse not only strong promoters to generate large quantities of mRNA, butalso ribosome binding sites to ensure that the mRNA is efficientlytranslated. In E. coli, the ribosome binding site includes an initiationcodon (AUG) and a sequence 3-9 nucleotides long located 3-11 nucleotidesupstream from the initiation codon (Shine, et al., Nature 254:34, 1975).The sequence, AGGAGGU, which is called the Shine-Dalgamo (SD) sequence,is complementary to the 3′ end of E. coli 16S rRNA. Binding of theribosome to mRNA and the sequence at the 3′ end of the mRNA can beaffected by several factors:

-   -   (i) The degree of complementarity between the SD sequence and 3′        end of the 16S rRNA.    -   (ii) The spacing and possibly the DNA sequence lying between the        SD sequence and the AUG (Roberts, et al., Proc. Natl. Acad. Sci.        (USA) 76:760.,1979a: Roberts, et al., Proc. Natl. Acad. Sci.        (USA) 76:5596, 1979b; Guarente, et al., Science 209:1428, 1980;        and Guarente, et al., Cell 20:543, 1980). Optimization is        achieved by measuring the level of expression of genes in        plasmids in which this spacing is systematically altered.        Comparison of different mRNAs shows that there are statistically        preferred sequences from positions −20 to +13 (where the A of        the AUG is position 0) (Gold, et al., Annu. Rev. Microbiol.        35:365, 1981). Leader sequences have been shown to influence        translation dramatically (Roberts, et al., 1979a, b supra).    -   (iii) The nucleotide sequence following the AUG, which affects        ribosome binding (Taniguchi, et al., J. Mol. Biol., 118:533,        1978).        The 3′ regulatory sequences define at least one termination        (stop) codon in frame with and operably joined to the        heterologous fusion polypeptide.

In preferred embodiments with a prokaryotic expression host, the vectorutilized includes a prokaryotic origin of replication or replicon, i.e.,a DNA sequence having the ability to direct autonomous replication andmaintenance of the recombinant DNA molecule extrachromosomally in aprokaryotic host cell, such as a bacterial host cell, transformedtherewith. Such origins of replication are well known in the art.Preferred origins of replication are those that are efficient in thehost organism. A preferred host cell is E. coli. For use of a vector inE. coli, a preferred origin of replication is ColE1 found in pBR322 anda variety of other common plasmids. Also preferred is the p15A origin ofreplication found on pACYC and its derivatives. The ColE1 and p15Areplicons have been extensively utilized in molecular biology, areavailable on a variety of plasmids and are described by Sambrook et al.,Molecular Cloning: A Laboratory Manual, 2nd edition, Cold Spring HarborLaboratory Press, 1989).

In addition, those embodiments that include a prokaryotic repliconpreferably also include a gene whose expression confers a selectiveadvantage, such as drug resistance, to a bacterial host transformedtherewith. Typical bacterial drug resistance genes are those that conferresistance to ampicillin, tetracycline, neomycin/kanamycin orchloramphenicol. Vectors typically also contain convenient restrictionsites for insertion of translatable DNA sequences. Exemplary vectors arethe plasmids pUC18 and pUC19 and derived vectors such as pcDNAIIavailable from Invitrogen, (San Diego, Calif.).

When the antibody of the invention include both heavy chain and lightchain sequences, these sequences may be encoded on separate vectors or,more conveniently, may be expressed by a single vector. The heavy andlight chain may, after translation or after secretion, form theheterodimeric structure of natural antibody molecules. Such aheterodimeric antibody may or may not be stabilized by disulfide bondsbetween the heavy and light chains.

A vector for expression of heterodimeric antibodies, such as the intactantibodies of the invention or the F(ab′)₂, Fab or Fv fragmentantibodies of the invention, is a recombinant DNA molecule adapted forreceiving and expressing translatable first and second DNA sequences.That is, a DNA expression vector for expressing a heterodimeric antibodyprovides a system for independently cloning (inserting) the twotranslatable DNA sequences into tavo separate cassettes present in thevector, to form two separate cistrons for expressing the first andsecond polypeptides of a heterodimeric antibody. The DNA expressionvector for expressing two cistrons is referred to as a dicistronicexpression vector.

Preferably, the vector comprises a first cassette that includes upstreamand downstream DNA regulatory sequences operably joined via a sequenceof nucleotides adapted for directional ligation to an insert DNA. Theupstream translatable sequence preferably encodes the secretion signalas described above. The cassette includes DNA regulatory sequences forexpressing the first antibody polypeptide that is produced when aninsert translatable DNA sequence (insert DNA) is directionally insertedinto the cassette via the sequence of nucleotides adapted fordirectional ligation.

The dicistronic expression vector also contains a second cassette forexpressing the second antibody polypeptide. The second cassette includesa second translatable DNA sequence that preferably encodes a secretionsignal, as described above, operably joined at its 3′ terminus via asequence of nucleotides adapted for directional ligation to a downstreamDNA sequence of the vector that typically defines at least one stopcodon in the reading frame of the cassette. The second translatable DNAsequence is operably joined at its 5′ terminus to DNA regulatorysequences forming the 5′ elements. The second cassette is capable, uponinsertion of a translatable DNA sequence (insert DNA), of expressing thesecond fusion polypeptide comprising a secretion signal with apolypeptide coded by the insert DNA.

The antibodies of the present invention may also, of course, be producedby eukaryotic cells such as CHO cells, human hybridomas, immortalizedB-lymphoblastoid cells, and the like. In this case, a vector isconstructed in which eukaryotic regulatory sequences are operably joinedto the nucleotide sequences encoding the antibody polypeptide orpolypeptides. The design and selection of an appropriate eukaryoticvector is within the ability and discretion of one of ordinary skill inthe art. The subsequent purification of the antibodies may beaccomplished by any of a variety of standard means known in the art.

In another embodiment, the present invention provides host cells, bothprokaryotic and eukaryotic, transformed or transfected with, andtherefore including the vectors of the present invention.

Diagnostic and Pharmaceutical Anti-RSV Antibody Preparations

The invention also relates to a method for preparing diagnostic orpharmaceutical compositions comprising the monoclonal antibodies of theinvention or polynucleotide sequences encoding the antibodies of theinvention or part thereof, the pharmaceutical compositions being usedfor immunotherapy of RSV disease. The pharmaceutical preparationincludes a pharmaceutically acceptable carrier. Such carriers, as usedherein, means a non-toxic material that does not interfere with theeffectiveness of the biological activity of the active ingredients. Theterm “physiologically acceptable” refers to a non-toxic material that iscompatible with a biological system such as a cell, cell culture,tissue, or organism. The characteristics of the carrier will depend onthe route of administration. Physiologically and pharmaceuticallyacceptable carriers include diluents, fillers, salts buffers,stabilizers, solubilizers, and other materials which are well known inthe art.

A preferred embodiment of the invention relates to monoclonal antibodieswhose heavy chains comprise in CDR3 the polypeptide PVANIDY (SEQ ID NO:7), and/or whose light chains comprise in CDR3 the polypeptideQSYDSENPWV (SEQ ID NO: 15) and conservative variations of thesepeptides. Also encompassed by the present invention are certain aminoacid sequences that bind to epitopic sequences in glycoprotein F of RSVwhich include aa residue number 429 or which are conformationallyaffected by a single change at aa residue number 429 from arginine toseine, and which confer neutralization of RSV when bound thereto. Theterm “conservative variation” as used herein denotes the replacement ofan amino acid residue by another, biologically similar residue. Examplesof conservative variations include the substitution of one hydrophobicresidue such as isoleucine, valine, leucine or methionine for another,or the substitution of one polar residue for another, such as thesubstitution of arginine for lysine, glutamic for aspartic acids, orglutamine for asparagines, and the like. The term “conservativevariation” also includes the use of a substituted amino acid in place ofan unsubstituted parent amino acid provided that antibodies having thesubstituted polypeptide also neutralize RSV. Analogously, anotherpreferred embodiment of the invention relates to polynucleotides whichencode the above noted heavy chain polypeptide and to polynucleotidesequences which are complementary to these polynucleotide sequences.Complementary polynucleotide sequences include those sequences whichhybridize to the polynucleotide sequences of the invention understringent hybridization conditions.

The anti-RSV antibodies of the invention may be labeled by a variety ofmeans for use in diagnostic and/or pharmaceutical applications. Thereare many different labels and methods of labeling known to those ofordinary skill in the art. Examples of the types of labels which can beused in the present invention include enzymes, radioisotopes,fluorescent compounds, colloidal metals, chemiluminescent compounds, andbioluminescent compounds. Those of ordinary skill in the art will knowof other suitable labels for binding to the monoclonal antibodies of theinvention, or will be able to ascertain such, using routineexperimentation. Furthermore, the binding of these labels to themonoclonal antibodies of the invention can be done using standardtechniques common to those of ordinary skill in the art.

Another labeling technique which may result in greater sensitivityconsists of coupling the antibodies to low molecular weight haptens.These haptens can then be specifically altered by means of a secondreaction. For example, it is common to use haptens such as biotin, whichreacts with avidin, or dinitrophenol, pyridoxal, or fluorescein, whichcan react with specific anti-hapten antibodies.

The materials for use in the assay of the invention are ideally suitedfor the preparation of a kit. Such a kit may comprise a carrier meansbeing compartmentalized to receive in close confinement one or morecontainer means such as vials, tubes, and the like, each of thecontainer means comprising one of the separate elements to be used inthe method. For example, one of the container means may comprise a humanmonoclonal antibody of the invention which is, or can be, detectablylabeled. The kit may also have containers containing buffer(s) and/or acontainer comprising a reporter-means, such as a biotin-binding protein,such as avidin or streptavidin, bound to a reporter molecule, such as anenzymatic or fluorescent label.

In Vitro Detection and Diagnostics

The monoclonal antibodies of the invention are suited for in vitro use,for example, in immunoassays in which they can be utilized in liquidphase or bound to a solid phase carrier. In addition, the monoclonalantibodies in these immunoassays can be detectably labeled in variousways. Examples of types of immunoassays which can utilize the monoclonalantibodies of the invention are competitive and non-competitiveimmunoassays in either a direct or indirect format. Examples of suchimmunoassays are the radioimmunoassay (RIA) and the sandwich(immunometric) assay. Detection of antigens using the monoclonalantibodies of the invention can be done utilizing immunoassays which arerun in either the forward, reverse, or simultaneous modes, includingimmunohistochemical assays on physiological samples. Those of skill inthe art will know, or can readily discern, other immunoassay formatswithout undue experimentation.

The monoclonal antibodies of the invention can be bound to manydifferent carriers and used to detect the presence of RSV. Examples ofwell-known carriers include glass, polystyrene, polypropylene,polyethylene, dextran, nylon, amylase, natural and modified cellulose,polyacrylamide, agarose and magnetite. The nature of the carrier can beeither soluble or insoluble for purposes of the invention. Those skilledin the art will know of other suitable carriers for binding monoclonalantibodies, or will be able to ascertain such, using routineexperimentation.

For purposes of the invention, RSV may be detected by the monoclonalantibodies of the invention when present in biological fluids andtissues. Any sample containing a detectable amount of RSV can be used. Asample can be a liquid such as urine, saliva, cerebrospinal fluid, bloodserum or the like; a solid or semi-solid such as tissues, feces, or thelike; or alternatively, a solid tissue such as those commonly used inhistological diagnosis.

In Vivo Detection of RSV

In using the monoclonal antibodies of the invention for the in vivodetection of antigen, the detectably labeled monoclonal antibody isgiven in a dose which is diagnostically effective. The term“diagnostically effective” means that the amount of detectably labeledhuman monoclonal antibody is administered in sufficient quantity toenable detection of the site having the RSV antigen for which themonoclonal antibodies are specific.

The concentration of detectably labeled monoclonal antibody which isadministered should be sufficient such that the binding to RSV isdetectable compared to the background. Further, it is desirable that thedetectably labeled monoclonal antibody be rapidly cleared from thecirculatory system in order to give the best target-to-background signalratio.

As a rule, the dosage of detectably labeled human monoclonal antibodyfor in vivo diagnosis will vary depending on such factors as age, sex,and extent of disease of the individual. The dosage of monoclonalantibody can vary from about 0.01 mg/kg to about 500 mg/kg, preferably0.1 mg/kg to about 200 mg/kg, most preferably about 0.1 mg/kg to about10 mg/kg. Such dosages may vary, for example, depending on whethermultiple injections are given, on the tissue being assayed and otherfactors known to those of skill in the art.

For in vivo diagnostic imaging, the type of detection instrumentavailable is a major factor in selecting an appropriate radioisotope.The radioisotope chosen must have a type of decay which is detectablefor the given type of instrument. Still another important factor inselecting a radioisotope for in vivo diagnosis is that the half-life ofthe radioisotope be long enough such that it is still detectable at thetime of maximum uptake by the target, but short enough such thatdeleterious radiation with respect to the host is acceptable. Ideally, aradioisotope used for in vivo imaging will lack a particle emission butproduce a large number of photons in the 140-250 keV range, which may bereadily detected by conventional gamma cameras.

For in vivo diagnosis, radioisotopes may be bound to immunoglobulineither directly or indirectly by using an intermediate functional group.Intermediate functional groups which often are used to bindradioisotopes which exist as metallic ions are the bifunctionalchelating agents such as diethylenetriaminepentacetic acid (DTPA) andethylenediaminetetra-acetic acid (EDTA) and similar molecules. Typicalexamples of metallic ions which can be bound to the monoclonalantibodies of the invention are ¹¹¹In, ⁹⁷Ru, ⁶⁷Ga, ⁶⁸Ga. ⁷²As, ⁸⁹Zr and²⁰¹Tl.

The monoclonal antibodies of the invention can also be labeled with aparamagnetic isotope for purposes of in vivo diagnosis, as in magneticresonance imaging (MRI) or electron spin resonance (ESR). In general,any conventional method for visualizing diagnostic imaging can beutilized. Usually gamma and positron emitting radioisotopes are used forcamera imaging and paramagnetic isotopes for MRI. Elements which areparticularly useful in such techniques include 157Gd, ⁵⁵Mn, ¹⁶²Dy, ⁵²Crand ⁵⁶Fe.

The human monoclonal antibody of the invention can be used in vitro andin vivo to monitor the course of RSV disease therapy. Thus, for example,by measuring the increase or decrease in the number of cells infectedwith RSV or changes in the concentration of RSV present in the body orin various body fluids, it would be possible to determine whether aparticular therapeutic regimen aimed at ameliorating the RSV disease iseffective.

Prophylaxis and Therapy of RSV Disease

The monoclonal antibodies can also be used immunotherapeutically for RSVdisease in both humans and other animals. The term,“immunotherapeutically” or “immunotherapy” as used herein in conjunctionwith the monoclonal antibodies of the invention denotes bothprophylactic as well as therapeutic administration and both passiveimmunization with substantially purified polypeptide products, as wellas gene therapy by transfer of polynucleotide sequences encoding theproduct or part thereof. Thus, the monoclonal antibodies can beadministered to high-risk subjects in order to lessen the likelihoodand/or severity of RSV disease or administered to subjects alreadyevidencing active RSV infection. In the present invention, Fab fragmentsalso neutralize RSV both in vitro and in vivo and therefore may be usedtherapeutically to treat RSV infection in vivo. As explained above, Fabfragments are preferred for topical administration to the lining of thelung but intact antibodies molecules are otherwise preferred.

As used herein, a “therapeutically effective amount” of the monoclonalantibodies of the invention is a dosage large enough to produce thedesired effect in which the symptoms of the RSV disease are amelioratedor the likelihood of infection is decreased. A therapeutically effectiveamount is not, however, a dosage so large as to cause adverse sideeffects, such as hyperviscosity syndromes, pulmonary edema, congestiveheart failure, and the like. Generally, a therapeutically effectiveamount may vary with the subject's age, condition, and sex, as well asthe extent of the disease in the subject and can be determined by one ofskill in the art. The dosage may be adjusted by the individual physicianor veterinarian in the event of any complication. A therapeuticallyeffective amount may vary from about 0.01 mg/kg to about 500 mg/kg,preferably from about 0.1 mg/kg to about 200 mg/kg, most preferably fromabout 0.2 mg/kg to about 20 mg/kg, in one or more dose administrationsdaily, for one or several days. Preferred is administration of theantibody for 2 to 5 or more consecutive days in order to avoid “rebound”of virus replication from occurring.

The monoclonal antibodies of the invention can be administered byinjection or by gradual infusion over time. The administration of themonoclonal antibodies of the invention may, for example, be intravenous,intraperitoneal, intramuscular, intracavity, subcutaneous, ortransdermal. When used therapeutically, a preferred route ofadministration of the monoclonal antibodies of the invention is bypulmonary aerosol. Techniques for preparing aerosol delivery systemscontaining antibodies are well known to those of skill in the art.Generally, such systems should utilize components which will notsignificantly impair the biological properties of the antibodies, suchas the paratope binding capacity (see, for example, Sciarra and Cutie,“Aerosols,” in Remington's Pharmaceutical Sciences, 18th edition, 1990,pp 1694-1712; incorporated by reference). Those of skill in the art canreadily determine the various parameters and conditions for producingantibody aerosols without resort to undue experimentation.

Preparations for parenteral administration include sterile aqueous ornon-aqueous solutions suspensions, and emulsions. Examples ofnon-aqueous solvents are propylene glycol, polyethylene glycol,vegetable oils such as olive oil, and injectable organic esters such asethyl oleate. Aqueous carriers include water, alcoholic/aqueoussolutions, emulsions or suspensions, including saline and bufferedmedia. Parenteral vehicles include sodium chloride solution, Ringer'sdextrose, dextrose and sodium chloride, lactated Ringer's or fixed oils.Intravenous vehicles include fluid and nutrient replenishers,electrolyte replenishers (such as those based on Ringer's dextrose), andthe like. Preservatives and other additives may also be present such as,for example, antimicrobials, anti-oxidants, chelating agents, and inertgases and the like.

EXAMPLE 1 Isolation of RSVF2-5 Monoclonal Antibody Fab Fragment

PCR amplification of Fab and library construction. Peripheral bloodlymphocytes were purified from 50 ml of whole heparinized blood of anHIV-1-infected donor, by single step density gradient usingHistopaque-1077 (Sigma Chemical Co., St. Louis, Mo.) and washed once inDulbecco's phosphate-buffered saline (PBS). Total RNA (30 mg) waspurified from peripheral blood lymphocytes using a rapid single stepguanidinium isothiocyanate/phenol chloroform-based RNA isolationtechnique (Stratagene, La Jolla, Calif.), and cDNA was generated byreverse transcriptase (RT) using Superscript RLNase H⁻ (Gibco-BRL, GrandIsland, N.Y.). PCR amplification of the IgG₁ Fd heavy chain fragmentsand light chains was performed for 35 cycles of 94° C.×1 min. 54° C.×1min, 72° C.×3 min. This was followed by a single incubation at 72° C.for 10 min. 5′ primers for the individual H and light chain V regiongene families, and 3′ constant region primers for IgG¹, k or 1 aspreviously described (Kang et al., in “Methods, A Companion to Methodsin Enzymology: Vol. 2”, R. A. Lemer and D. R. Burton, ed. AcademicPress, NY, pp 111-118,1991), were obtained from Operon (Alameda,Calif.). Primers contained restriction enzyme sites to allow thesequential ligation of Fd and light chain libraries into the phagedisplay vector. Fd fragment DNA, of approximately 699 base pairs, wasamplified with sites for the restriction enzymes, Xho I at the-5′ end ofthe V_(H) domain, and Spe I at the 3′ end of the C_(H1) domain, forligation with DNA encoding the cap protein, or gene III product. Lightchain DNA, of approximately 639 base pairs, was amplified with sites forthe restriction enzymes, Sac I at the 5′ end of the V_(L) domain, andXba I at the 3′ end of the C_(L) domain. The vector, pAbClone, wasconstructed from pcDNAII (Invitrogen, San Diego. Calif.) and pET20b(Novagen, Madison, Wis.) (pelB leaders), to contain DNA encoding the capprotein of the M13 filamentous phage, derived from M13 mp18 (Stratagene,La Jolla, Calif.), with a restriction site for Spe I at the 5′ end forligation to the 3′ end of DNA encoding the Fd fragment, essentially asdescribed by Barbas et al. (Proc. Natl. Acad. Sci. (USA) 88:7978-7982,1991). Infection of phagemid-bearing E. coli with VCSM13 helper phage(Stratagene) allowed production of a packaged phage library, with phagesimultaneously expressing Fab molecules on the phage bad and carryingDNA encoding the Fab molecules within the phage body.

Cloning and expression of Fab molecules. From a packaged phagemidlibrary of 10⁷ clones, Fab binding to RSV Long strain (ATCC VR-26)proteins (abV Immune Response, Derry, N.H.) were enriched by 4 rounds ofpanning. RSV proteins were bound to microtiter 96 well plates (Costar.Cambridge, Mass.) at 1 mg/well in 25 ml 0.1 M NaHCO₃, overnight at 4°C., as previously described (Burton D. R., et al., Proc. Natl. Acad.Sci. (USA) 88:10134-10137, 1991). Amplification of the eluted phagebetween each round was performed by infection of E. coli XL1-Blue cells(Stratagene, La Jolla, Calif.) and packaging with VCSM13 helper phage(Stratagene, La Jolla, Calif.). Panning resulted in a 100-fold increasein the relative yield of eluted phage when compared to the secondpanning. DNA encoding the phage cap protein was then excised bydigestion with NheI and SpeI, and the compatible ends of the vectorrelegated to allow production of soluble Fab molecules. Clones producingsoluble Fab binding to RSV proteins were then identified by ELISA, usingalkaline phosphatase conjugated goat anti-human Ig F(ab′)₂ (Pierce,Rockford, Ill.).

Production and purification of Fab. For screening of soluble Fabproducing clones, 10 ml overnight cultures in super broth (24)/50 μgCarbenicillin/ml (SB/Carb) were induced with 1 mMisopropyl-(beta)-D-thiogalactopyranoside (IPTG). The next morningcultures were centrifuged (4000 g for 10 min) and cell pellets werefreeze/thawed three times in PBS/200 mM PMSF/0.01% NaN₃(PBS/PMSF/Azide). Lysates were centrifuged (100,000 g for 5 min) and 50μl volumes of supernatants were used in place of serum dilutions, asabove, for ELISA testing. Purified Fab were produced from cell pelletsof 1 liter cultures in SB/Carb, as described above. Pellets werefreeze/thawed, as above, in 25 ml PBS/PMSF/Azide and centrifuged at14,000 g for 40 min, filtered through a 0.22 mm filter and applied to a10 ml Sepharose-4B (Pharmacia Biotech Inc., Piscataway, N.J.)/goatanti-human F(ab′)₂ (Pierce, Rockford, Ill.) affinity column equilibratedwith PBS. After washing with 700 ml of PBS, the Fab were eluted in 50 mlof 0.2M glycine (pH 2.5), neutralized by addition of 1/10 of a volume of1M Tris (pH 9.0) and concentrated to 1 ml in a Centriprep 30concentrator (Amicon, Beverly, Mass.). Purified, concentrated Fab wereanalyzed on Coomassie Blue-stained SDS-PAGE gels, run under reducingconditions, at between 1-10 μg per lane, and were greater than 95% purein all cases.

Isolation and characterization of human Fab binding to RSV proteins.After 4 rounds of panning the library of 10⁷ clones with RSV proteins(Table 1), eight clones were isolated, which were producing solublehuman Fab binding to RSV proteins. RSV protein-binding Fab were purifiedfrom the periplasmic extracts of lysed cell pellets from 1 litercultures of XLI-Blue, by affinity chromatography. The approximatebinding constants were determined for these clones by ELISA using thepurified Fab. Only one of these Fab clones designated RSVF2-5, wasspecific for RSV proteins and did not react with BSA or other viralproteins. The protein expression level for the RSVF2-5 Fab varied from500-700 mg purified protein/I of culture. DNA sequences were determinedfor the Fd and light chain to allow cloning into vectors for genetictherapy (presented as SEQ ID NO: 21 and SEQ ID NO: 22) and thetranslated amino acid sequences are presented in Table 5 and as SEQ IDNO: 1 and SEQ ID NO: 9. Analysis of DNA insert size, molecular weightsof purified expressed proteins on SDS-PAGE gels and translated DNAsequences revealed RSVF2-5 to consist of an Fd fragment and light chain(Fab fragment). Alignment of DNA sequences with the Genbank databaseidentified the Fd fragment as belonging to the V_(H3) gene family andthe light chain to be a lambda chain of the V_(L6) gene family. (Table5). A predominance of lambda light chains in the original library (l:kDNA ratio was ˜9:1) was the result of constraints imposed by theoriginal yield of total RNA and a limited yield of k chain DNA from PCRamplification.

Fab binding constant determinations. RSV proteins were bound to ELISAplates at 0.1 mg/ml and blocked with 3% BSAIPBS, as above. Serialtwo-fold dilutions of purified human Fab in 1% BSA/PBS were added towells (50 μl/well), incubated and washed, as for ELISA titrations above.Goat anti-human F(ab′)₂ alkaline phosphatase conjugate (Pierce,Rockford, Ill.) and p-nitrophenyl phosphate solution were then addedsequentially with washing between, as described above. The bindingconstants were determined as the Fab concentration (g/l) at 50% bindingdivided by the approximate molecular weight of the Fab (5×10⁴). Bindingconstant determinations were performed at least twice, on two separatebatches of purified Fab.

The approximate binding constant for the human anti-RSV protein FabRSVF2-5 was determined to be 8.7×10⁻⁹ M from ELISA titration of purifiedFab.

DNA sequencing. Double stranded plasmid DNA was purified by Qiagenplasmid maxiprep kit (Qiagen, Chatsworth, Calif.). Sequencing was thenperformed on an automated 373A DNA sequencer (Applied Biosystems, Inc.(ABI), Foster City, Calif.), using a Taq fluorescent dideoxy terminatorcycle sequencing kit (ABI). Both 5′ vector flanking sequences specificto Fd (SEQ ID NO: 17, T3, 5′-ATT AAC CCT CAC TAA AG-3′) or light chain(SEQ ID NO: 18, KEF, 5′-GAA TTC TAA ACT AGC TAG TCG-3′) leaders and 3′primers (SEQ ID NO: 19, SeqGz 5′-GAA GTA GTC CTT GAC CAG-3′) for theC_(H1) or (SEQ ID NO: 20, SeqLb 5′-GAA GTC ACT TAT GAG ACA CAC-3′) forthe C_(L) domains, respectively, were employed. Derived sequences forheavy chain Fd fragments and light chains were aligned using MacVectorand the Genbank database (International Biotechnologies Inc., New Haven,Conn.).

RSV Fab F2-5 specifically binds to RSV F glycoprotein. The specificityof RSVF2-5 for the RSV F glycoprotein was demonstrated by ELISA bindingusing purified RSV F or G glycoproteins, prepared as previouslydescribed (Walsh, et al. J. Gen. Virol. 65:761-767, 1984 and Walsh. etal. J. Gen. Virol. 66:409-415, 1985). A 1 μg/ml purified preparation ofRSVF2-5 exhibited a titer of >1: 16,384, while a similarly preparedsuspension of a hepatitis B Fab (also 1 μg/ml) had a 1:2 titer in thesame test. This preparation of Fab RSVF2-5 did not bind purified Gglycoprotein, as evidenced by an ELISA titer of <1:2, while anRSV-positive adult control serum exhibited a titer of 1:4,096 in thesame test.

Virus neutralization assay. Neutralization of RSV virus isolates,representing 10 isolates each from antigenic subgroups A and B, isolatedover a period of 31 years from several national and internationalcenters, was tested by a plaque reduction neutralization assay (Coates,et al., J. Epid., 83:299, 1966), using Vero cell monolayer cultures. Thetiter of neutralizing antibody was expressed as the highest dilution ofaffinity purified Fab which reduced the plaque number by 60%. Results ofneutralization testing of the affinity purified RSVF2-5 Fab, againstthese RSV isolates, are shown in Table 2. Efficient neutralization ofthese RSV isolates was observed between 0.2 to 3.0 μg/ml for all of thevarious isolates from subgroups A and B. Hence, RSVF2-5 has broadreactivity and is highly efficient in neutralizing activity, against thetwo antigenic subgroups of RSV. These data also indicate that thetemporal stability of the neutralization epitope, identified by thehuman Fab RSVF2-5 is very high, being stable over a 31 year period.Titration of the same purified Fab preparation used for the subgrouptesting, with the strain RSV A2, in the same in vitro test, indicated a60% plaque reduction neutralizing titer of 1:803,471 and hence aspecific activity of 0.005 μg/ml. Crude E. coli lysates were not testedin this assay, due to the non-specific results frequently obtained withthis type of crude Fab preparation.

EXAMPLE 2 The Therapeutic Efficacy of Human Monoclonal Fab RSVF2-5 inTreating RSV Infected Mice

Clearance of RSV from the lungs of infected mice by purified RSVF2-5Fab. Groups of six mice were infected intranasally (i.n.) with 10⁷ pfuof RSV strain A2, in 100 μl of sterile PBS, under light methoxytluraneanesthesia, on day 0. Four days post infection, representing the heightof the infection, different groups were treated with the indicated dose(Table 3) of affinity purified Fab in 100 μl of sterile PBS, instilledintranasally under the same conditions of anesthesia as for inoculationwith virus. The ELISA titer of this purified Fab preparation, at aconcentration of 3.6 mg/ml, was 1/60,000, the neutralization titer was1/803,471 (Example 1) and the purity was greater than 99%. Control micewere treated with PBS or with a human monoclonal Fab (HBVc41) isolatedfrom the same combinatorial Fab library, which binds to hepatitis Bvirus (HBV) core antigen (Table 3). Lung tissue homogenates and nasalturbinates where prepared for virus quantitation on day 5 (18 hours postFab treatment) (Murphy et al., Vaccine 8:497-502, 1990 and Prince etal., Am. J. Path. 93:771-792, 1978) and stored frozen until they weretitered for RSV on Vero cell monolayers by plaque reduction assay(Coates, et al., J. Epid. 83:299, 1966). Plaques were detected byimmunoperoxidase labeling as described by Murphy et al. (1990).

The human anti-RSV Fab RSVF2-5 was highly effective in clearing anestablished RSV infection from the lungs of mice (Table 3). Detectablevirus was evident in the lungs of only 1 out of 6 mice treated with 4.0mg/kg of body weight with a mean reduction of more than 3 log₁₀ pfucompared to that produced by treatment with the HBV core antigen Fab(HBVc41) or PBS.

EXAMPLE 3 Identification of the RSVF2-5 Binding Epitope

The following example demonstrates that the human Fab RSVF2-5, whichneutralizes RSV in vitro and cures mice of lung infection with RSV,identifies an epitope (linear or conformational) which includes the Fglycoprotein amino acid (aa) residue number 429 or which isconformationally affected by this residue.

Neutralization of escape mutants of the RSV strain A2. Monoclonalantibody RSV escape mutants (MARM) were tested for in vitroneutralization by human monoclonal Fab RSVF2-5, using the plaquereduction assay described in Example 1 (Coates. et al., J. Epid. 83:299,1966), on Vero cell monolayers. The titer of neutralizing antibody wasexpressed as the highest dilution of affinity purified Fab which reducedthe plaque number by 60%. Results of neutralization testing of thepurified RSVF2-5 Fab, against these RSV are expressed in Table 4.Affinity purified anti-RSV Fab RSVF2-5 does not neutralize the RSV MARMv324 of Dr. G. Taylor, generated using the mouse monoclonal antibody(MAb) RSV19 (Taylor et al., Immunology 52:137-142, 1984). In contrast,RSVF2-5 Fab neutralized all other escape mutants and the wild type RSVstrain A2 with neutralizing titers in the same range as that for thesubgroup A and B RSV isolates tested in Example 1 (Table 2). The MARMv324 escape mutant of RSV possesses a single aa substitution (arginineto serine) at residue 429 on the F1 subunit of the RSV F glycoprotein.However the aa sequences of the RSVF2-5 human Fab V_(H)- andV_(L)-regions (Table 5) are unique and unrelated to those of the RSV19MAb or the humanized form of this mouse antibody (see, e.g., PCTInternational Publication Number WO92/04381).

Hence the present invention recognizes a neutralization epitope on theRSV F glycoprotein F1 subunit which either includes arginine residue 429or which is remote from this residue but is affected conformationally bya substitution at that position. The associated paratope of the RSVF2-5human Fab defined by the CDR-regions, in particular CDR3 of the of theV_(H)- and V_(L)-regions is suitable for the preparation of protectiveand therapeutic agents which neutralize RSV, in particular, for thepreparation of monoclonal antibodies against the associated epitope onthe RSV F glycoprotein. Knowledge of this paratope enables one of skillin the art to produce synthetic peptides or anti-idiotypic antibodieswhich may also be suitable as vaccines against RSV. The epitopeincluding, or conformationally affected by, substitution at residue 429on the RSV F glycoprotein F1 subunit, identified by the RSVF2-5 humanFab, is a suitable target for the screening of other neutralizationepitopes and the production of monoclonal antibodies useful for thetherapy and prophylaxis of RSV infections in humans.

RSVF2-5 was deposited at the American Type Culture Collection, 10801University Blvd., Manassas, Va. 20110-2209 under ATCC Designation 69909.

The foregoing written specification is to be considered to be sufficientto enable one skilled in the art to practice the invention. The presentinvention is not to be limited in scope by the cell line deposited,since the deposited embodiment is intended as a single illustration ofone aspect of the invention and any cell lines that are functionallyequivalent are within the scope of the invention. Similarly, thenucleotide sequences and particular antibodies disclosed herein are notto be construed as limiting of the invention as they are intended merelyas illustrative of particular embodiments of the invention as enabledherein. Therefore, any sequences or antibodies that are functionallyequivalent of those described herein are within the spirit and scope ofthe claims appended hereto. Indeed, various modifications of theinvention in addition to those shown and described herein will becomeapparent to those skilled in the art from the foregoing description andfall within the scope of the appended claims.

TABLE 1 ENRICHMENT OF PHAGE FROM PANNING OF CARU LIBRARY WITH RSVPROTEINS Pan round Applied phage* Eluted phage* Relative yield 1 2.4 ×10¹² 3.3 × 10⁷ 1.2 × 10⁻⁵ 2 1.1 × 10¹³ 9.1 × 10⁶ 8.0 × 10⁻⁷ 3 1.4 × 10¹²7.1 × 10⁷ 4.9 × 10⁻⁵ 4 3.0 × 10¹¹ 2.6 × 10⁷ 8.5 × 10⁻⁵ *Total number ofcfu in 200 ul of PBS/1% BSA

TABLE 2 NEUTRALIZATION OF RSV STRAINS FROM ANTIGENIC SUBGROUPS A AND B,BY HUMAN MONOCLONAL Fab RSVF-2-5 RSV Virus Specific neutralizationIsolates# activity (μg/ml)* Subgroup A SW/669/′59 3.0 Wash/11657/′60 1.6Wash/Bern/′65 0.6 SL/863/′84 0.2 SL/10849/′84 0.9 SL/10865/′84 0.4OK/9970/′85 1.4 Bir/6190/′89 2.4 New/RSS-2/′76 1.9 Bir/1734/′89 1.1Subgroup B WV/474R/′90 0.9 WV/1293/′75 1.0 WV/4843/′80 0.5Wash/18537/′62 0.5 WV/14617/′85 2.6 WV/17154/′85 2.1 WV/20323/′87 0.8WV/285R/′90 0.6 WV/401R/′90 0.7 WV/2B/′87 0.3 *Quantity of purified Fabrequired, for preincubation with virus, to effect a reduction of 60% inRSV induced plaques, produced in Vero cell monolayers #Abbreviations:Bir (Birmingham), New (Newcastle), OK (Oklahoma), SL (St. Louis), SW(Sweden), Wash (Washington), Wash/Bern (Washington/Bern) and WV (WestVirginia). (West Virginia strains provided by M. A. Mufson, M.D.).

TABLE 3 THERAPEUTIC EFFECT OF PURIFIED RSVF2-5 HUMAN ANTI-RSV Fab IN RSVINFECTED MICE Dose RSV titer in tissue homogenate* (mg Fab/kg (meanlog₁₀ pfu/g tissue) Treatment body weight) Nasal turbinates Lungs FabRSVF2-5 4.0 3.2 1.9= 1.0 3.8 3.3 0.25 4.4 4.3 0.0625 4.2 4.0 0.0156 5.04.9 0.0039 4.9 5.2 HBVc41 Fab 4.0 4.7 5.3 1.0 4.7 5.3 PBS n.a 4.5 5.2*Titer of virus recovered from tissue homogenates 4 days post infectionwith RSV and 18 hours post treatment with affinity purified Fab or PBS.#Virus recovered from 1 of 6 animals at 1.7 log₁₀ pfu/g detectable. Meancalculated using 1.7 for the 5 animals without detectable virus.

TABLE 4 NEUTRALIZING ABILITY OF RSVF2-5 FOR MONOCLONAL ANTIBODY ESCAPEMUTANTS OF RSV RSV Dose for 60% plaque Antigenic Amino acid MARM*reduction (μg/ml) site substituted# v1237 <0.3 A 276 v1214 0.1 A 276v1129 0.5 A 275 vN151 0.4 A 272 v1200 0.3 A 272 v1153 0.9 A 262 v1269<0.3 B 389 v1308F 1.0 C 241/421 v1302A/1 1.4 C 241/421 v1302A/6 <0.3 C241/421 v324† >18 other 429 A2 w.t.** 0.1 na na *Monoclonal antibody RSVescape mutants (MARM) generated from the RSV strain A2 by Dr. GeraldineTaylor. #Amino acid (aa) substitutions on the RSV F glycoproteinresponsible for the resistance to neutralization. †v324 is a MARMresistant to mouse MAb RSV19 of Geraldine Taylor, the humanized form ofwhich is the subject of international patent application numberWO92/04381. The MARM possesses a single aa change at position 429 (F1subunit). ** Wild type RSV strain A2.

TABLE 5 V-REGION AMINO SEQUENCES OF RSVF2-5 Fd AND LIGHT CHAIN RegionHeavy Chain VH3 Sequence Light Chain VL6 Sequence FR1 LEESGGDLVQLTQPHSVSES PGRSLRLSCS LGKTVTISC TSGFSFG (SEQ ID NO: 10) (SEQ ID NO: 2)CDR1 DYPVN TRAGGRIASN (SEQ ID NO: 3) YVQ (SEQ ID NO: 11) FR2 WFRQAPGKGLWYQQRPGSSP EWLG TTVIY (SEQ ID NO: 4) (SEQ ID NO: 12) CDR2 IVRSRLYGGTEDNQRPF LQYAASVEG (SEQ ID NO: 13) (SEQ ID NO: 5) FR3 RFTISRDDSKGVPDRFSGSI SIAYLHMNSL DTSSNSASLT KSEDTAVYYC ISGLKTEDEA GV DYYC (SEQ IDNO: 6) (SEQ ID NO: 14) CDR3 PVANIDY QSYDSENPWV (SEQ ID NO: 7) (SEQ IDNO: 15) FR4 WGQGTLVTVS FGGGTKLTVL SASTKGPSS G (SEQ ID NO: 8) (SEQ ID NO:16)

1. A pharmaceutical preparation comprising: a pharmaceuticallyacceptable carrier; and a substantially pure antibody selectivelybinding an RSV F glycoprotein epitope, wherein said antibody consists ofthe amino acid sequence of SEQ ID NO: 7.